First, it must be understood that the Proto-Indo-Europeans and their descendants, the Indo-Europeans, are not a race but a culture. This must be accepted, lest we fall into the trap of Aryanism. There is no Indo-European race, but linguists have reconstructed, using comparative linguistics, what may have been the language, religion, and cultural environment of the original Indo-Europeans.

Likely originating on the Russian Steppes, or perhaps around what is now Kyrgistan, the Indo-Europeans developed as a distinct group some time in the fifth millennium BCE, when they descended upon the area south of the Black Sea and the Balkans. By the second millennium BCE, they had developed into distinct groups like the Hittites, MyceneanGreeks, and Indo-Iranians. At this point, we cannot speak of Proto-Indo-Europeans or Indo-Europeans, but of distinct cultures.

There has been some recent debate as to how closely the Indo-European culture is related to the Semitic; while it is not believed to be descended of the Semitic, some scholars are willing to admit that there does seem to be some religious, if not linguistic, ties. This only makes sense, given the close proximity of the two cultures. The preponderance of deluge myths, symbolism involving trees and snakes, ritualized meals and dying and rising gods seem to point to either an influence, or perhaps a close heritage, of the two groups, though not a close common origin, given the disparity in the language systems. (Admittedly, all humans have a common origin.)

: The reconstructed names which I feature here are brought courtesy of Ceisiwr Serith, who has devoted a number of pages on his website to the subject; I also know Serith, however cursorily, through ADF, and respect the work he's done. Still, for the sake of completeness, I've also provided the hypothetical roots of his reconstructions. Also, many of the roles will overlap; for example, both Tyr and Odin are listed under Dyeus Pater, for various reasons.